1. Field of the Invention
The present invention relates to parachute systems that are environmentally sealed to extend the parachute""s repack cycle and overall useful life. More specifically, the present invention relates to an improved linkage system coupling the external parachute harness to the parachute risers, which are enclosed within the environmentally sealed bag protecting the parachute system.
2. Background of the Invention
Parachute systems typically comprise a harness, a container, a pilot parachute (pilotchute) or a drogue parachute, and a main parachute. Typically a parachute has multiple suspension lines joining the main parachute, i.e., the sail or canopy, to one of two risers which are connected to the harness worn by the parachutist. The connection between the harness and the risers must bear the load of any forces reacting between the parachute and parachutist. The main parachute is packed in a deployment bag with the suspension lines folded and loosely tacked to the outside of the bag. The deployment bag and suspension lines are housed in the parachute container which may form part of the parachute harness. The pilotchute is attached to the deployment bag and may also be stored in the parachute container.
During normal operations, when the parachutist pulls a ripcord or some other means for deploying the parachute is activated, the pilotchute is released into the air stream. The pilot chute pulls the deployment bag out of the parachute container, thereby extending the suspension lines and risers. Eventually, the deployment bag opens releasing the main parachute, and the parachutist""s weight will be supported by the main parachute through the risers and suspension lines.
Details on the current state-of-the-art of U.S.-manufactured personnel parachutes, their materials, design, construction, repair, and packing may be found in The Parachute Manual, a Technical Treatise on Aerodynamic Decelerators, by Daniel F. Poynter, Para Publishing, P.O. Box 4232, Santa Barbara, Calif. 93103-0232 (1984), which is expressly incorporated by reference herein. U.S. military specifications for personnel parachutes are presented in Military Specification MIL-P-85710(AS), Parachutes, Personnel, Emergency Escape, General Design Specification for, Department of Defense, Washington, D.C. 20301, Mar. 5, 1986, which is also expressly incorporated by reference herein.
It is known in the art that the life of a parachute system is increased significantly if the parachute is environmentally sealed. The environmentally sealed package protects the parachute from harmful environmental agents such as moisture, mildew, fungus, ultraviolet light, and smog. Environmental sealing typically comprises enclosing the parachute deployment bag (storing the main parachute), the suspension lines and the risers within a vacuum-sealed package (xe2x80x9cvacuum bagxe2x80x9d) made of an environmental barrier material, thereby protecting those components from exposure. Even though the risers are enclosed in the sealed package, they must still be connected to the parachutist""s harness, which is external to the environmental envelope, so that there is a structurally sound connection between the parachute system and the parachutist. U.S. Pat. No. 5,253,826 discloses a sealed parachute and a linkage system for joining the risers to the harness without breaking the environmental seal. U.S. Pat. No. 5,253,826 is expressly incorporated by reference herein.
Even when a parachute system has been environmentally sealed, the life of the parachute will be shortened if the integrity of the seal is not maintained. A common problem experienced with conventional parachutes having such sealing or packaging is damage or fatigue in the area where the sealed parachute risers structurally interfaces with the parachute harness. In the prior art, the sealed risers are connected to the harness via a linkage system made of structural metal connectors and a bushing, as described in U.S. Pat. No. 5,253,826. This linkage system provides a rigid connection between the two parachute components, which causes external bending, compression, and tension forces on the linkage to be transmitted to the environmental envelope. This causes the package to fatigue and then leak, thus breaching the environmental seal.
A need therefore exists for an improved linkage system for connecting an environmentally sealed parachute system to a parachute harness system wherein said linkage system does not transfer certain forces from outside of the sealed envelope to components inside the seal.
The present invention is a flexible linkage system providing a structurally sound connection between an environmentally sealed apparatus, such as a parachute, and an external apparatus, such as a parachute harness. The flexible linkage system comprises a flexible internal riser link, housed completely within the environmentally sealed parachute bag, and a flexible external riser link attached to the harness. The internal and external riser links, when connected together, provide a structural path to support the loads placed on the system upon opening of the parachute. Both the internal riser link and the external riser link can be made of fabricated textile materials providing significant flexibility that prevents bending and fatigue of the environmental or vacuum package. Such textile material should have high strength and low tenacity providing sufficient flexibility without being susceptible to damage.
The internal riser link is attached at one end to the parachute""s suspension lines. On the other end a loop is formed. The environmental envelope completely encloses the parachute, including the internal riser link. The loop must be large enough to allow the sealing material to be sealed in the center of the loop with enough space to allow a hole, centered in the loop, to be cut through the material. Prior to cutting the hole, the sealing material is reinforced with material applied over the looped area of the internal riser link. The external riser link is attached to the harness on one end and connects to the internal riser link on the other end as described below.
The external riser link comprises a webbing strap attached to the parachute harness at one end. The external riser link may be permanently fixed to the harness or may be removably attached, i.e., the external riser link may be detached from the harness if desired. The other end of the webbing strap is fed through the looped end of the internal loop and the end is secured to a middle section of the webbing strap using attachment hardware.
In a preferred embodiment, the external riser link further comprises a webbing loop, a cord loop, an anchor loop, and a removable fastener. The webbing loop is threaded through the environmental envelope and looped end of the internal riser link. The cord loop is then passed through the webbing loop and connected to the anchor loop with the removable fastener. The removable fastener used on the external riser link permits easy connection or disconnection of the external riser link to the internal riser link.
It is an object of the present invention to enhance the canopy suspension line to harness interface that is used for environmentally sealed parachutes. This significantly increases the environmentally sealed parachute repack cycle from the present cycle of about five and a half years or less to up to seven years or longer, by devising a enhancing the environmentally sealed that inhibits aging of the parachute.
It is another object of the present invention to enhance the environmental sealing or vacuum sealing for all types of parachutes, including but not limited to, emergency bail-out, ejection seat, space vehicle recovery, cargo delivery, and sport reserve parachutes.
It is another object of the present invention to provide a linkage system enhancing the environmental or vacuum sealing of parachutes having varied design shapes, including but not limited to, conventional round, parafoil/ram-air, ribbon, or cruciform parachutes.
It is another of the present invention to provide a flexible linkage system for connecting a parachute riser to the parachute harness wherein the parachute and parachute riser a completely enclosed within an environmentally sealed envelope.
It is another object of the present invention to extend the life of an environmentally sealed parachute by providing a flexible linkage system that does not wear or damage the environmental sealing enclosing the parachute.
It is another object of the present invention to provide a strong but flexible linkage system for between a parachute riser and a parachute harness.
It is another object of the present invention to provide a simple to use flexible linkage system for connecting a parachute riser to a parachute harness.
These and other objects of the present invention will be apparent from the description and the accompanying drawings of a preferred embodiment of the present invention.